Newly-published love letters from Ronald Reagan to his wife Nancy have revealed a tender side of the former US president, including the startling disclosure that he called her "Mommie Poo Pants".

In a book entitled "I Love You Ronnie", published on Thursday, Mrs Reagan exposes her husband's intimate outpourings of love in letters, cards and telegrams in an attempt to show his "private side".

The president pined for his wife while on tours

The correspondence spans more than 40 years, beginning when they were both minor film stars.

It ends with Mr Reagan's famous address to the nation in 1994, when he acknowledged that he was suffering from Alzheimer's Disease and was heading into the "sunset of my life."

The 89-year-old former president rarely appears in public now due to his illness.

Pet names

According to the letters, many of which are illustrated with pictures of tiny hearts, the couple had many pet names for one another, including "1st Poppa", "Your In Luv Guv" and "Mommie Poo Pants."

Other intimate details, including touching descriptions of his wife while she was sleeping and the extent to which the president missed his wife on officials tours of the country, are revealed.

M - is for the misery of which I have none

O - means only that without you I would die

M - is for how very much (when we're apart) I miss you

M - is for the million ways I love you

Y - Yippie!! I'm so happy

Another letter, in which the president salutes his wife on the couple's 29th wedding anniversary in 1981 begins:

"Dear First Lady...as President of the US, it is my honour and privilege to cite you for service above and beyond the call of duty in that you made one man (me) the most happy man in the world for 29 years."

The letters reveal a deep and enduring love

Much of the book is narrated by Mrs Reagan and describes their 48-year marriage.

She says that until her husband was diagnosed in 1994 with the degenerative brain disease, there were no symptoms of Alzheimer's.

While the book is primarily about the Reagans' marriage, Mrs Reagan does refer to the Iran-Contra scandal, which shadowed much of her husband's second term in office.

The secret scheme to divert money to anti-government rebels in Nicaragua led to televised congressional hearings, in which White House aide Oliver North was indicted and Chief of Staff Donald Reagan was forced to resign.

Mrs Reagan says her husband had been "badly served by people who were supposed to aid and advise him".

She describes a report in which an independent investigator says impeachment should have been considered as "baseless".

Despite the scandal, for most Americans, Mr Reagan was the plain-speaking president who left office with the highest approval rating of any incumbent of the White House.